Alternator warning light resistor May 6, 2024 · Battery warning light vs Alternator (replaced the globe with a LED) Jump to Latest 1. . Jun 5, 2007 · I bought one for "65 w/ gauges", which is different than "65 w/ warning lights". I have read If your exciter wire is part of that circuit and the bulb burns out, the circuit fails, and no charge happens. Jan 19, 2018 · No cluster, then no working alternator. If its electrical circuit has failed, that will effect the alternator charging, as the current through the electrical circuit of the alternator/ignition warning Jul 29, 2016 · warning (idiot) light. Or You could wire up a voltage comparator circuit and the LED that tells you you have less than 13Volts. Mar 1, 2017 · With power and ground supplied, the charge warning light will illuminate. Any 12v DC light will work just fine. Also, if your ALT exciter circuit is a warning light, make sure it’s not burned out and functional. Mar 29, 2011 · The circuit was meant to have an alternator light in it, the resistor is simply to simulate a light bulb if you choose not to use one. light. But as I mentioned, if the wire is frayed somewhere, you might get able to get 12v, or just enough amperage to light the LED, but not enough amperage delivered to the alternator exciter circuit. If you use an AMP light, you probably won't even need a resistor -- the light is a resistor. If you don't have or want a light, use a resistor. Does this go in parallel or in series with the led bulb and what resistance should I use, any ideas? Feb 10, 2020 · Years back I used a resistor wire to excite the 10SI in my car. The resistor is to provide more current to make sure the alternator gets started. The report noted: "It was apparent that the ALT caption, which illuminates whenever there is no output from the alternator, mounted between two other warning lights on the instrument panel, was very dim… Nov 6, 2014 · 3. Apr 25, 2007 · The resistor is a probably a 1/2 watt part soldered to the instrument panel circuit board. 5v depending state of charge) to rectifier output (battery voltage plus junction voltage of diode). If its electrical circuit has failed, that will effect the alternator charging, as the current through the electrical circuit of the alternator/ignition warning It is recommended that an SI to CS conversion having an warning light present use JT&T #2771F adapter (a voltage gauge package can be present, but must include a warning light). requires a hot wire from battery, a ground, and hot wire from key, and a 12 volt supply going through the charge warning lamp. Jun 19, 2016 · There is a 500 ohm resistor in parallel with the warning light so that if the bulb burns out, the regulator still gets the exciter voltage. 2 volts (Charging) going into the battery. It has worked fine for 5 years now. Some alternators have it internally and simply need a second direct feed from the ignition switch Where they dont it will be somewhere in the panel or wiring. It is actually a necessary component of the charging system. Current flows through the Gernerator Field Winding. I've found the various useful threads in the archives about diagnosis and solution and just wanted to check that the 40 Ohm version of one of these is what I need (I've linked to the 50 Ohm version because there's not a nice picture of the 40 Ohm version): Feb 12, 2024 · An LED device is intrinsically a diode, albeit light emitting, so a small LED will probably require a limiting resistor to supply the required amount of voltage and current, which may be relatively lower vs an incandescent bulb, typically as low as 50 milliamps. Engine off, ignition on, battery fully charged 1. 25 amps Apr 12, 2020 · The operation handbook circuit diagram shows the light bulb circuit goes though a diode and resistor to ground and is back biased to turn it off only when the alternator in running. The warning light supplies an exciter voltage that tells the regulator to Apr 9, 2014 · The original alternator warning light is usually around 2/3W but the LED will be much lower than that and it may not go out even though the alternator is charging, the solution is to add a shunt resistor across the legs of the LED, the value depends on the spec of the LED. Apr 9, 2013 · The original alternator no charge light works by a voltage difference between a separate alternator terminal & 12v at the battery. I have an oil pressure gauge and I added a warning light for that too. Mar 22, 2019 · Led Alternator Warning Light - Resistor - posted in Problems, Questions and Technical: I no longer have a filament bulb, so I believe the circuit needs a resistor adding so the Alternator will charge the battery. Aug 10, 2014 · The dim warning light is usually because there is a bad diode in the alternator. Disconnect the D connector with the 3 wires (yellow/white, white/black and green/red) from the voltage regulator. I recently put LEDs in my instrument cluster, and did a few warning lights for consistency. BLK from alternator BAT+ to battery + is Ford cuircuit 37. Sep 11, 2022 · You can use an LED indicator light there with a 50Ω-100Ω 5 Watt shunt resistor in parallel with the LED. Replaces AC/Delco #8078, PT2145, D-856A. I used this (539-FL1M8SW-1-R12V) from Mouser. It's simple and elegant and it works fantastic. Apr 27, 2004 · Now the power feed to the field circuit is via the ignition switch and idiot light in series. The original alternator no charge light works by a voltage difference between a separate alternator terminal & 12v at the battery. Such a resistor is sometimes fitted so that if the bulb goes there is still start up excitation. You should then have 13. It's called bootstrapping as the GEN light provides some current to the rotor of the alternator to start the alternator. I was having some alternator issues too, and added a secondary rule: If (battery warning light = true AND rpm > 500) Then throw an big red alert on the screen: Charging System Failure! Oct 8, 2022 · This resistor is used to excite an alternator warning light circuit. Oct 4, 2015 · The alt. It is also recommended to use a warning light or wire resistor when installing ? failure to do so could damage Aug 25, 2016 · No cluster, then no working alternator. Jan 20, 2013 · Note however, that you should also connect a 50 Ohm resistor in parallel with the light, so that if the bulb burns out, the alternator will still be excited. Now if a parallel resistor is placed across the idiot globe, and the globe should blow, power is still supplied through the resistor. You could also use just a resister and and no warning light if you have a voltmeter. Think the harness was mid-70's. Feb 12, 2024 · An LED device is intrinsically a diode, albeit light emitting, so a small LED will probably require a limiting resistor to supply the required amount of voltage and current, which may be relatively lower vs an incandescent bulb, typically as low as 50 milliamps. Jul 2, 2024 · Case Study 1: Resistor and Warning Light Issues. Essentially the voltage from the half wave rectifier will be very close to the battery voltage (which may be at 16v due to the overcharge from the alternator). Yes, with a resister you can have a warning light and sufficient current to kick off the field. Dec 18, 2021 · There are 4 posts pos,neg, w for tachometer and the other for warning light, Ive swapped the signal wires to no avail the pos has two red cables, one from starter the other to instrument panel, the neg post has two, one to the block the other is a return neg from instrument gauges. That wire goes to a dash light. It won't affect the bulb. Could this type resistor wire be used to run through the LED light, to excite the alternator? Pretty sure the wire was single strand. Jan 8, 2023 · This is an important wire to understand if you are connecting an alternator warning light. Car is 1981 911SC, alternator is believed to be original w/ external regulator. Jun 13, 2009 · What's the purpose of the Ignition Light Resistor in my 1987 110 2. Here is more info on the Lamar sensor from a Beech Lister, Mike Ter. Unplug the wire from the alternator and it should go off. No glow, bulb has burned out or there is a break or bad connection in the wiring between the regulator plug and the instrument cluster. There is a warning light on the fiero dash that comes ON when the alternator stops charging. The warning light supplies an exciter voltage that tells the regulator to Jun 14, 2020 · Wiring a 100 ohms resistor in parallel with the Tyco's coil gives TYCO 90 Ohm Plus 100 Ohm Resistor In Parallel = 47. Oct 22, 2007 · One of the two wires on a two wire light needs to run to a switched( you only want the light to come on with the ignition switch) voltage source. But if you don't have a light the alternator won't kick on so they put a resistor there. May 3, 2016 · Yes, that will work, and if you want to get the LED to light as well, you need the following info. Alternator Warning Light Resistor 10 Watt. John T Aug 15, 2017 · The 12 volts coming through the bulb excites the alternator to start charging, once the alternator starts charging the green wire is no longer a ground it has 12 volts so the warning light is off. Mar 17, 2016 · Problem is that kit does not provide a way to drive alternator charge light. I installed an LED light/fixture, and now the car won't start. Mar 2, 2009 · The number 1 wire goes to a resistor or dash light and is suppose to glow when not charging. The light should burn bright with the engine off and key on. The bulb will light when you turn the switch on before the alternator starts spinning though, just like every car, so you get a test of the bulb every time you start. Nov 7, 2024 · The bulb of the alternator warning light/ignition warning light does not simply serve the function of a 'Warning Light'. Therefore if the idiot light globe blows no power is supplied to the alternator field circuit and hence no charging. Solution: Upon testing, the resistor showed a resistance of 156 ohms instead of the required 68 Apr 24, 2018 · I've fallen foul of the problem of the alternator not being activated having replaced the ignition/alternator light with an LED version. Quantity: Add to Wishlist. Swap out the resistor for something suitable for the voltage you are using. If there is no factory idiot light available in the dash, I might put the light bulb at the alternator, or I might use a resistor, or a diode, depends on the car. All things are possible. Once the engine runs and the alternator is charging no current flows and the light goes out. It can't be more than 3W because the regulator isn't designed to handle more than that. If no warning light is present, use JT&T #2770F adapter. All new wiring, not factory stuff. Should you buy a 12V LED, it will have the necessary voltage drop down resistor in it. I like red lights shining at me to alert me to problems. If you have an ammeter in your instrument cluster, take the GRN/RED (I terminal) and WHITE (F terminal) wires at the regulator plug, remove them from the plug and connect them together using a 100 ohm, 10 watt resistor (see photo below) between the 2 wires. My alternator warning light is not coming on when I start the car. Today I checked that the proper voltage is coming out of the alternator at the pcb board with the resistor mounted on it that the alternator out sensor monitors - It is fine. It would have green, black and brown bands, and a 4th band that would be gold or silver. If the warning light bulb burns out no electricity will pass through it and the charging system won't work so the resistor provides another path for the electricity to flow through to keep the Oct 27, 2011 · Without a warning light, appropriate resistor, or diode in the "excite" circuit, the alternator can charge OUT of the excite terminal, causing the engine to continue to run after the ignition switch is shut off, and/or possibly damaging the diode trio or internal voltage regulator. May 7, 2015 · I don't think there is a resistor in that circuit. Most hot rodders and muscle car enthusiasts prefer the use of a volt meter or ammeter to monitor charging. 368 Ohms Current = 12 divided by 47. 87 * 0. It mentions putting a 91 ohm 5 watt resistor across the bulb. : The basic circuit of the Lamar alt inop sensors is: Green wire gives ground for warning light through the sensor's black wire. The alternator uses the voltage from the warning light circuit as a signal to turn on and start charging. I'm going to get a Aug 16, 2021 · This will preserve the function of your alternator warning lamp with the new alternator. They didn't have room (or want the cost) for the tach and ammeter so they added the warning light instead of the ammeter and the light needs the resistor so the alternator will continue to operate if the light burns out. Replaces GM #12102921, 88861073, 90196375. Apr 27, 2006 · The fix is to add a small resistor across (in parallel with) the dash warning light. Mar 8, 2015 · Might be teaching grandmother to suck eggs but as I understand it, the logic works like this: One side of the Warning light is 12V+ ignition switched, the other side is connected to the alternator output. It should not glow dim with the engine running. The warning light didn’t come on during ignition, indicating a possible issue with the resistor or the bulb. If the warning light burns out, the resistor takes over and supplies the regulator with a turn on signal. 2533355 Say 0. May 4, 2012 · jesse, go to napa ask em for a amber 12v push in light, (same light Howell uses for a check engine) An LED will NOT work and will burn up the alt. Alternator is different from dynamo, it needs an initial dose of current to 'excite' the winding to give sustaining voltage. So… (1) Load test the battery, (2) confirm the impedance of the battery and alternator cables, (3) have the alternator tested by an ignition specialist. When the alternator terminal is at 12v the light goes out. If the resistor did not have as high a rating as the bulb, then it literally becomes that famous "path of least resistance" and though the alternator will work, the light will never light up. Maybe someone can help me understand this. I have about 3 volts on terminal plugged in to alternator and light is on, with key on and engine off. The resistor needs to be a 5 Watt rated resistor, and it will get warm (hot) if the key is left in the run position with the engine off and the light is on, or when the alternator fails. It is also recommended to use a warning light or wire resistor when installing ? failure to do so could damage the alternator. However, once the alternator energizes almost no current will flow through the lamp. Mar 11, 2014 · I plan on installing a charge light between the alternator terminal 1 and the ignition Switched IGN terminal. Weight. Thus I have a voltage gauge and I added a warning light. Feb 13, 2024 · At full field the alternator will definitely put out 16+v, depending on the condition of the battery. I think the only way I can sense charge is to compare battery output (12v nominally, but of course +/- 1. 00. Mustangs Unlimited has different part numbers for "65 6cyl w/ warning lights" and "65 8cyl w/ warning lights", so now I'm trying to figure out the differences. Connect the warning light's positive terminal directly to the alternator's output post. 7K views 36 replies 8 participants last post by krietpiel May 9, 2024 Nov 7, 2024 · The bulb of the alternator warning light/ignition warning light does not simply serve the function of a 'Warning Light'. Dec 12, 2013 · Circuit Operation: With the Ignition Switch in Start or Run, Battery voltage is applied through the Gage Fuse and the Generator Warning Light to terminal L (brown wire) of the Gernerator on models equipped with warning indicator. Dec 30, 2016 · If you want to use a led warning light in the dash (like I do because of size/looks/style) you can parallel it with a regular warning light (like a common #194) or a diode, hidden under the dash. Feb 9, 2009 · The field current comes from the warning light connection, so it gets power from either the warning light or from the alternator windings, via the 3 small diodes. 5 N/A Diesel? I'm wondering if this resistor could be reason why the battery warning light doesn't come off by itself when I start the engine. Aug 30, 2024 · My limited understanding of the charging circuit is that the small green wire going to the D+ terminal of the alternator senses battery voltage, via a resistor in the ARC circuitry (or in 'normal' cars, via the alternator warning light on the dash). Youll run one wire from the alt to one side of the bulb and keyed 12v to the other the light will illum with the key on and as soon as u start the engine and begin charging it will go out. The resistor takes the place of the bulb if it burns out so the alternator still gets excited to start charging. i guess it applies to any engine, stock or swapped. My issue is I'm using an LED as my warning light, which changes the voltage equation, and no one - NO one, can give me a reliable plan for how to use an LED in this Apr 5, 2016 · Seems hat without the Resistor the Generator LIght emits a soft glow when the key is turned off allowing the engine to run on. 043A, barely enough to light an LED. I have 12 volts from warning lamp with it unplugged from alternator and light is off, key is on. 5-14. Type RESISTOR. Failure to Apr 30, 2019 · HOWEVER if you go with an idiot light charge indicator use a small INCANDESCENT BULB NOTTTTTTTTTT AN LED BULB A diode or a resistor or an idiot light can (among other methods) wire in series between the ignition switches IGN output or the coils input to the small 1R terminal on side of alternator. GRN/RED from warning light to regulator 'I' (warning light circuit) or from ignition switch to regulator 'S' terminal (ammeter circuit) is Ford circuit 904. The schematic shows that one side of the light (black/green) gets power from a splice at the head of the pink resistor wire that goes to the coil and the other side of the light (green/red) goes to the "I" terminal on the regulator. switch is putting power May 29, 2020 · I prefer the idiot light. How it works is when the Alt. I understand the "special function" the lamp has and the consequences of it not coming on. The 40 ohm Resistordraws current and the Warning Light glows. Apr 1, 2016 · The resister is used to provide 'excitation' current to the alternator winding during initial startup. Normally, the battery light provide a path for the excitation current so the resister is not needed. Then Alternator Warning Light Resistor 427 ONLY SKU# ALT009. 3) Ensure there is a good ground connection between the bare alternator case, the mounting bracketry and the engine block/heads and/or install a dedicated ground wire from the engine block . Problem: The vehicle’s alternator wasn’t charging until the engine reached high RPMs. 39 ohms * 033 amps = 12. The bulbs and/or diodes are not needed to excite a 3-wire GM 10/12 SI; they simply prevent engine run-on when the 12 V is cut with the ignition switch May 11, 2012 · The '96 Camaro I took my engine from had a 470 ohm resistor in parallel with the warning light. If the wiring in this circuit is broken, the alternator doesn't charge and the battery goes dead. DO NOT wire #1 terminal directly to ignition “ON”: it either must be connected to the warning light or a 400-ohm resistor, NOT connected directly to the ignition. Jan 10, 2012 · They consist of a LED with a current limiting resistor with a resistor to provide the current needed to excavate the alternator so it will start charging 2 calculations are needed 24V - the forward voltage of the LED divided by the forward current of the LED 20 mA The parallel resistor will be (24 V) ² divided by the wattage of the existing Lamp May 14, 2020 · The warning light bulb has less than 15 ohms resistance so as long as the bulb works the electricity will pass through it rather than the resistor. What's the likelihood that the light could burn out? If so, would it leave me stranded? Aug 23, 2013 · If the engine and alternator package is designed to operate with LED warning lights this resistor will exist somewhere. If this light bulb is burnt out, the alternator will NOT charge and the battery goes dead. This is my question: Is the wire coming off the alternator + or - ? Jan 8, 2022 · If (amperage across the isolator is > 0A for greater than 0. Nov 8, 2024 · My alternator (ignition) warning light stopped working in my 72 mgb - Alternator stopped working, but car ran as long as battery was charged. What should it be in parallel with? As someone has said a 47ohm resistor in parallel that is connected in effect across the charge warning light contacts will double the excite current if the light is 3 watt. The resistor wire came out of GM pickup harness, that had the optional voltmeter in the gauge package(no idiot light). It is there as a backup for the alternator warning light. Apr 30, 2024 · On the Stangs, it doesn't matter if there is a tach or not- its not in that circuit. Ok Aug 18, 2015 · Bulb check will tell you if your alternator warning light itself is working if there are no other problems. If you get run-on after adding the resistor, stick the diode shown above Mar 22, 2019 · Led Alternator Warning Light - Resistor - posted in Problems, Questions and Technical: I no longer have a filament bulb, so I believe the circuit needs a resistor adding so the Alternator will charge the battery. The alternator warning lamp circuit begins at the "common" battery-side lug of the starter solenoid and goes through the ignition switch, then IN SERIES through the warning lamp bulb (which also should have a 560 ohm "bridge resistor across its terminals") to the voltage regulator "I" terminal. I used an LED and wired a 470 ohm resistor in parallel to match the factory arrangement. Long story short. For example, when I ran an MSD ignition in my truck, I used a resistor, and it would not shut off when turning off the key, so I added a diode. Is this a direct con Apr 4, 2021 · Typically tho, the L wire is also used as a dash warning indicator (idiot light) in-line with the wire and a resistor in-line to decrease the voltage into the alternator/regulator. 24 Watts, so a 5 watt resistor is cut Jun 5, 2011 · Some time ago I came across this Air Accident Investigation Branch report concerning a PA32R that landed gear-up following an alternator failure. Not much of a "warning lamp" in that case! Feb 12, 2024 · An LED device is intrinsically a diode, albeit light emitting, so a small LED will probably require a limiting resistor to supply the required amount of voltage and current, which may be relatively lower vs an incandescent bulb, typically as low as 50 milliamps. Connecting An Alternator Warning Light To connect an alternator warning light, you will need to locate the ignition switch, the alternator, and the warning light. Price: $16. However, certain Tuff Stuff alternators like the 7127, 7139 and 7140 series have terminals that may be used for a warning light. The actual path of this circuit is: Battery + to fuse to relay (controlled by key-on source from factory wiring harness, I think R/LB if I recall correctly) to Alt Warn light (and other gauges/lights, all in parallel) and then back to the voltage regulator LG/R wire. Feb 12, 2019 · Yeah, 300 ohms on 13V only passes 0. To wire a warning light, remove the terminal plug cover and connect the #1 (Left terminal, looking from the back of the alternator) to the warning light wire. Nov 21, 2024 · Diagnosing a possible battery and/or alternator issue at the same time on the same circuit is extremely hard. I suspect a bad connection since it functions sometimes. 87 volts across the resistor and power dissipated = 12. just going through my car and thought id share what the dummy light does and how to hook it upit excites the alternator when the key is turned ON and is resi Aug 7, 2020 · The alternator won't kick on properly without some current flowing in the path and it's traditionally done by lighting up the warning light. is not running it allows the current from the light to go to ground ,the light will light because the Ign. Battery Cut Off Switch with key. To wire a warning light using one of these alternators, simply Jul 13, 2009 · I changed out the Alternator out sensor that mounts on the firewall with a new one. I also heard that those that did put an LED put a resistor or a regular bulb within that circuit. Aug 2, 2021 · The light should illuminate with the key on engine not running, once started, alternator turning, The "L" terminal should now produce 12 volts and no longer light the idiot light. Does this go in parallel or in series with the led bulb and what resistance should I use, any ideas? Jul 9, 2021 · The indicator lamp you're using likely has a current-limiting resistor in series with the LED making it suitable for use with 12V. (I will pull the bulb this weekend and check it and the voltage Aug 16, 2022 · The resistor is just there to provide more current to get the alternator started. If the charge warning light illuminates with the engine running, a fault is indicated. It still does not work. If its electrical circuit has failed, that will effect the alternator charging, as the current through the electrical circuit of the alternator/ignition warning Nov 6, 2023 · Only going through the resistor when the bulb fails. Forget about the diode, it's probably a needless complication. 368 = 0. It's only the alternator warning light that is staying on. Would you know the location of the diode and resistor and how to access it? Also the value of the resistor. Heavy duty rotary Nov 22, 2021 · 12V switched source -> alternator warning bulb -> resistor (for the LS alternators) -> pin B (exciter wire terminal/positive side of the voltage regulator) When ignition is switched on, current flows from the battery, through to the alternator warning lamp, through the voltage regulator and to ground, hence the bulb illuminates. Mar 19, 2021 · Obviously the issue began with the Painless harness. Aug 28, 2017 · There is a 500 ohm resistor in parallel with the warning light so that if the bulb burns out, the regulator still gets the exciter voltage. If there is little warning light current, there is little field current, and you can get the situation where the alternator doesn't generate even if it spins. I have connected the lead from the separate alternator terminal to the relevant wire on the dash 2 but the light does not go out. With ignition on, but engine not running, the warning light is grounded through the field winding, when the engine is started, the windings are self energised from the running alternator to ~ battery volttage ans so there is no tpotential and so no current to illuminate the light - note, sometimes the field wind voltage will exceed the voltage Hi Guys Just in the process of refitting my dashboard back after changing it back to original,I have fitted an LED for the ignition warning light along with the resistor in parallel across it. I'm thinking it might be length of wires, thinking the alternator position would be the only difference. It’s more difficult with variable output devices regulating things dynamically. Should I just switch my alternator warning light back to the incandescent bulb asap? Vehicle in question is a '94 Pathfinder. So when the ignition is switched on the warning light goes on as May 14, 2011 · 'a' resistor indicates a single resistor. BLK/WHT from alternator STATOR to regulator 'S' terminal is Ford circuit 4. Model 1974-83 911/T. Raw voltage from the alternator stator post (aux Jun 14, 2020 · It's a key-on 12v power source that supplies power to the gauges and the OP warning light. The other wire runs to the Alternator. Aug 31, 2021 · Use a test light. The Dash light has 2 terminals one for neg and one for positive. May 4, 2006 · Need a little input. ) The alternator warning light should glow. Once I rev the engine up a little bit, the light disappears and the battery seems to be charging OK. VIEW DETAILS. I have checked the wiring under the cowling - it all checks out. The resistor creates enough resistance to stop the run on and it seems its also needed with the new AAW kit as well. My alternator failed about a year ago and I replaced it (and its regulator) with a vendor Jan 19, 2018 · No cluster, then no working alternator. That’s the reason a 500 ohm resistor can be installed to keep that circuit up. Failure to Apr 15, 2017 · GOOGLE it. Try the 100 Ohm 2 watt resistor (or anything close to that). 33 = 4. Lamp should work as follows: 1) Key off, lamp off off Feb 13, 2024 · At full field the alternator will definitely put out 16+v, depending on the condition of the battery. 03kg. 4. Or will light up only dimly and at inconsistent times. When the generator is providing sufficient voltage with the engine running, the ground is opened and the charging warning light will not illuminate. 5seconds), then it activates the battery warning light. Jim - the light is grounded by the regulator-rectifier (not powered) upon fault detection. Feb 14, 2009 · As shown in the diagrams posted by DAUNTLESS46, about 10-15 ohms. 100 Ohms will add 120 ma of excitation current initially which should be enough to get the alternator going even at low RPM's. pevz xrobu qaapqvr aozhcy htwja eryrme aywa fwgzg prn oorazo